Systemic Hypertension in Cats

My 10 year-old cat had a surgery at the veterinarian’s. Before surgery, they heard a heart murmur during his physical examination. That led them to check his blood pressure, and he was diagnosed with systemic hypertension (high blood pressure). Is this like hypertension in people?

Blood pressure measurement evaluates the pressure against the walls of arteries during the time the heart contracts and empties itself of blood- systole- as well as during the time the heart relaxes and fills with blood- diastole. “Systemic hypertension” describes high blood pressure throughout the entire body, and this means a sustained elevation in systolic pressure of 140mmHg or greater, in diastolic pressure of 90mmHg or greater, or both.

"'Systemic hypertension’ describes high blood
pressure throughout the entire body"

Cats can experience temporary elevations in blood pressure due to stress effects, including just being in a veterinary hospital. It is important to take several readings and to create as quiet an environment as possible. Hypertension in cats is often due to an underlying disease and is called “secondary hypertension”. If no underlying disease is present or can be identified, then it is called “primary hypertension”.

Hypertension is more common in older cats, consistent with the development of underlying disease such as chronic kidney disease, or excessive levels of thyroid hormone from a functional (but benign) thyroid tumor. Younger cats may develop hypertension if they have kidney disease due to infection (such as leptospirosis) or a developmental kidney abnormality.

What are the signs of hypertension?

There are some signs of hypertension that can be observed. These include:

Sudden blindness, bleeding inside the globe of the eye, and persistently dilated pupils

Increased drinking and urinating with the progression of chronic kidney disease

Blood in the urine (called “hematuria”)

Bleeding in the nose and nasal passages (known as “epistaxis” or a “nosebleed”)

Heart murmurs or abnormal heart rhythms

What causes hypertension?

The cause of primary hypertension is unknown. Secondary hypertension accounts for a majority of hypertension in cats, and can be attributed to kidney disease, thyroid disease, diabetes mellitus (less common), pheochromocytoma (adrenal gland tumor and very uncommon), or central nervous system disease (very rare).

How is hypertension treated?

The treatment of cats with hypertension depends upon the underlying cause, if any. If the cat develops a serious complication related to hypertension like acute kidney failure or bleeding into the eye, there may be a need for hospitalization. In general, once any underlying condition is appropriately managed, medication and nutrition are important to normalizing blood pressure.

"Therapeutic nutrition is generally accepted
as an important part of long-term management.”

Medications that are commonly used to manage hypertension in cats include angiotensin converting enzyme (ACE) inhibitors and calcium channel blockers. Additional medications may be required depending upon the response to initial therapy. Therapeutic nutrition is generally accepted as an important part of long-term management.

What kind of monitoring will be required?

The treatment goal for a cat with hypertension is a systolic pressure of 140mmHg or less, and a diastolic pressure of 90mmHg or less. Periodic laboratory testing will be required to monitor for side effects of medication and progression of disease.

Potential complications of hypertension in the cat include:

Congestive heart failure

Chronic kidney disease

Retinal degeneration and subsequent blindness

Bleeding into the eye

Stroke (cerebral vascular accident)

What is the prognosis for hypertension?

The course of feline hypertension is dictated by the underlying cause. When blood pressure is well managed, the risks for potential complications are minimized. Medication for hypertension is generally a lifetime undertaking, and may be adjusted over time as needed.